<form [formGroup]="contactForm" (submit)="onSubmit()">
  <div formGroupName="fullName">
    <input type="text" formControlName="firstName" />
    <input type="text" formControlName="lastName" />
  </div>
  <button (click)="onPatchValue()">patchValue</button>
  <button (click)="onSetValue()">setValue</button>
  <button (click)="onReset()">reset</button>
  <button>提交</button>
</form>
